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mermaid and narwhal strawberry cake recipe (and tutorial): sky-girl’s seventh birthday

happy birthday, sky-girl! mermaids and narwhals forever! ::::

It’s hard to believe that Sky-Girl is seven years old! She completely directed the cake theme this year. She continues to be an enthusiastic helper at home, bright-eyed and usually pretty chipper, and best of all, a great giver and lover of hugs. The hardest thing about the COVID-19 pandemic has been having to stifle this hug reaction with friends and our need to physically distance from friends and faraway family (major disappointment from kids AND adults about having to cancel our trip to see family in Maine this summer). When I come home from work, I immediately get into the shower, no hellos or hugs allowed until I’m washed and in fresh clothing. It feels mean and counter what she is so comfortable doing to say to her, “No, you can’t hug me right now.” But we’ve all gotten used to it. And I know it won’t last forever. Keep hugging, Sky-Girl. Everyone says you give the best hugs and we like that you practice on us all the time.

So, the custom cake. I did a Pinterest review for ideas, cleared them with Sky-Girl, and got to work figuring out sizes and ingredients.

First, fondant. Then, cake. Last, frosting and assembly.

Fondant — I did not make my own blobs to save on time. I bought the Wilton brand, untinted. I like the homemade fondant better for taste, but it’s a little less predictable on hardening, even with the tylose (I clearly need to experiment more).

Adding a sprinkle of tylose powder into a handful of fondant helps stabilize and harden the fondant faster. I kneaded this in the pliable, white fondant before tinting with color. In a humid climate this is imperative. Here’s what I used:

I drew a mermaid tail free-hand on paper to use for the fondant tail — I actually made two tails but Sky-Girl chose the one below. I chose to keep this one untinted. Once dry, I painted this with watery food gel colors of blue, teal, pink, and lavender. I made the scale imprints with the wide edge of the piping tip you see in the photo below. The fin lines were done with a toothpick. The toothpicks at the bottom of the tail are used to stabilize the tail when poked into the cake. The toothpicks need to be added before the fondant starts to dry.

Here are the painted tail with added edible silver glitter, the teal tail with glitter, “bubbles” — balls of blue and white fondant mixed together, and coral. The kids helped make the coral twists (and made some seaweed later too). The chopsticks were set up under the tail fins to curve them while drying. These dried on an 11×17-inch pan, for scale.

Onto the narwhal! I looked at various cake decorations for inspiration and came up with my own plan. I knew the solid fondant would be heavy and topple if it didn’t have supports. I also had to figure out how to dry it with the supports in it without mashing the finished piece.

First, I took a 10.6 ounce white fondant piece and tinted it with one drop each of two colors: Americolor Black and Sky Blue. The oval below is my in-process narwhal body.

The yellow-gray thing underneath the gray lump is the start of the narwhal horn. I tinted a small piece of fondant with yellow and added a smaller piece of the gray. (I covered the horn with glitter, so it really didn’t matter that I made it this color, but wanted to have a back-up plan in case the glitter didn’t stick.)

Shaping and addition of the horn toothpick to stick into the narwhal body:

More shaping of the narwhal half body with fins, lopping off the back end, inserting lollipop sticks in the bottom for stabilizing, and poking the horn into place. I used a little of high grain alcohol mixed with the gold disco dust edible glitter and painted it on the horn. Important note: My paint brush did gum up a bit and I had to rinse it frequently.

The hardest part was how to position the narwhal to dry without bending the horn. If placed flat on its back, the back would flatten too much and the horn would droop. Using a wide glass with a piece of balled up foil at the end to lift the horn solved this issue. This glassware is from one of the recycled wine bottles I used to make drinking glasses, blog post here.

And the tail. I made the neck of the tail long enough to obviate the need for toothpick supports. The other shapes here are leftover fondant bits I rolled out and cut with an aspic cutter for a different cake.

I set all the decorations to dry undisturbed for three days. The narwhal needed this extra time, whereas the smaller, thinner pieces took two days.

Now the next day (or you can start the same day as the fondant), it’s time for the strawberry cake. I used 2 pounds of strawberries for the puree. I pureed them and got just over 4 cups.

The original recipe cooked down 1 pound of berries and said it would take about 30 minutes to cook down to 1 cup of a thick  concentrate. My double batch took over an hour and I ended up with a little more than 2 cups. My puree also did not look ruby red with all the cooking. It turned dark mauve. I mixed with the rest of the batter and ended up with a light mauve. You can add pink food coloring if that seems offputting.

I baked two 9-inch layers, one 7-inch layer, and had a little leftover for a short 6-inch cake layer. I used the two 9-inch layers and the one 7-inch layer for the cake below.

The frosting is the creamy, custardy German buttercream recipe I used on Sky-Girl’s fifth birthday cake here. I made the custard the night before, to save time with the cooling step, as it must be completely cool before adding the butter and mascarpone. I had extra after decorating, so need to need to double the recipe. The only change I made was to add the color: one to two drops each of Americolor Sky Blue and Teal. (I don’t remember exactly.)

The mermaid tail and narwhal await their pedestal:

See the recipe instructions for more info on the decoration placement.

We put a call-out to our wonderful neighbors to have a socially distanced celebration, each of us in our own driveways. One family could not make it and decorated our driveway with chalk instead! There’s even a mermaid at the bottom!

After cake sampling, Sky-Girl headed right for the narwhal. This thing was dense — she did not finish it but gnawed on it for a good while for a sugar rush. Neighbors also provided the cute narwhal horn she’s wearing.

Happy Birthday, sweet girl! I love you! Here’s to another year! Thank you, neighbors for making this year extra sweet despite our physical distancing!


One year ago: gudetama cupcakes (Sky-Girl’s sixth birthday)

Two years ago: rainbow cake (gum paste topper tutorial) with german buttercream frosting (recipe) (Sky-Girl’s fifth birthday)

Three years ago: bourbon cherries (My prep for our trip to Japan in 2017. We celebrated Sky-Girl’s fourth birthday at Mount Fuji.)

Four years ago: minnie mouse cake roll (for her third birthday)

Five years ago: hello kitty cake roll (the second birthday)

Five and a half years ago: We celebrated Sky-Girl’s first birthday about six months late and it coincided with the blog’s fourth anniversary: pandan chiffon cake

Six years ago: goodbye, california!

Seven years ago: mummy’s fudgy chocolate oatmeal bars recipe – and our new arrival (the birth of Sky-Girl)

Eight years ago: thai iced tea and butterfly purple ombre cake

Nine years ago: cranberries all around and honeyed goat cheese tart


mermaid and narwhal cake - sky-girl's seventh birthday
Recipe type: Dessert
Cake recipe from Sally's Baking Addiction ( I doubled her recipe and used two 9-inch pans and one 7-inch pan for the cake, with a little leftover for a short 6-inch cake (which was not used for the final cake). I doubled her recipe, which is reported as such below. Also, I did not use her frosting recipe. I used the German buttercream recipe from a previous post of mine: .
  • 2 pounds hulled, fresh strawberries (thawed, frozen berries are fine but take longer to cook)
  • 5 cups (500 g) sifted cake flour (spooned, leveled)
  • 4 teaspoons baking powder
  • 1 teaspoon baking soda
  • 2 teaspoons salt
  • 1½ cups (3 sticks or 340 g) unsalted butter, softened to room temperature
  • 3½ cups (700 g) granulated sugar
  • 10 large egg whites, at room temperature
  • ⅔ cup (125 g) sour cream, at room temperature
  • 4 teaspoons pure vanilla extract
  • 1 cup (240 ml) whole milk, at room temperature (don't use skim or 2%)
  • 1 cup reduced strawberry puree (SEE ABOVE)
  • FOR THE FROSTING: Follow my German Buttercream recipe ( and add blue/teal food coloring
  • FOR THE FONDANT DECORATIONS: pre-made fondant (or make your own -, tylose powder to help harden it, food coloring gels, and edible ink pens for drawing narwhal eyes.
  • OTHER SUPPLIES: toothpicks and lollipop sticks for fondant decoration support, chopsticks to hold drying decorations in place, 9-inch cake pan (x2), 7-inch cake pan, Americolor food color gels (Black, Sky Blue, Teal, Yellow, Red, Green, Pink, Purple), silver and gold edible glitter (disco dust).
  1. IMPORTANT NOTES: Get started early! The fondant shapes must be completely dry before placing on the cake. I started a few days in advance. The strawberry puree must be completely cool before using in the cake. I made the puree in the morning to cool in the fridge before baking the cake layers. Similarly, the German buttercream custard must be totally cool before mixing with the butter and mascarpone. The custard was made the night before I made the frosting the day of the cake-decorating. I'll break it up below:
  2. MAKE YOUR FONDANT SHAPES: I choose to use premade fondant this time, to save time. I mixed in a sprinkle or more of the tylose powder to help strengthen and harden it. Give the drying time about 3 days, especially if you have thick shapes like a narwhal.
  3. MAKE YOUR CAKE LAYERS: Puree the berries in a food processor.
  4. Over medium-low heat and stirring occasionally, reduce the strawberry puree to about 2 cups (I had a little more). Allow it to cool to room temperature before using in cake. Reduction took over an hour for me. This can be made a few days in advance, covered, and stored in the fridge. It can also be frozen for months and thawed before using.
  5. Preheat oven to 350°F (177°C). Grease and lightly flour or use parchment paper in two 9-inch cake pans and one 7-inch cake pan. There will be a little leftover batter (I used in a 6-inch pan and ate it separately.)
  6. Whisk the cake flour, baking powder, baking soda, and salt in a large bowl. Set aside.
  7. Use a stand mixer fitted with a whisk attachment to beat the butter and sugar together on high speed until smooth and creamy, about 2 minutes. Scrape down if needed.
  8. Beat in the egg whites on high speed until combined, about 2 minutes.
  9. Beat in the sour cream and vanilla extract. Scrape down again if needed.
  10. Run the mixer on low while adding the dry ingredients. Mix until just incorporated.
  11. With the mixer still running on low, slowly pour in the milk until just combined. Don't overmix!
  12. Whisk in 1 cup of reduced strawberry puree. Use 1 drop of food coloring if you want more pink. (Use the leftover puree for smoothies or drinks. I froze it in an ice cube tray.)
  13. Pour batter evenly into cake pans.
  14. Bake the 9-inch layers for about 25 minutes and the 7-inch layer about 20 minutes, or until each has a clean cake tester. Every oven is a bit different, so check a few minutes before these times to gauge how fast the layers are cooking.
  15. Cool cakes completely in the pans set on a wire rack. I cooled and wrapped in plastic wrap for a day before assembly the day of the celebration.
  16. THE NIGHT BEFORE OR DAY OF, MAKE THE BUTTERCREAM: I made the custard step of the buttercream the night before to save on cooling time waiting. I finished the buttercream the day of assembly because I didn't want to chill the buttercream and need to re-whip it in the morning before use. See my link here for the recipe: .
  17. My only addition was Americolor Sky Blue and Teal to make the buttercream "ocean."
  18. ASSEMBLY: Decorating is very unfussy. I didn't try to smooth everything out nor did I do a fancy crumb coat. Between the 9-inch layers, I used a thick layer of buttercream, dolloped on more "ocean" on the sides and top, then added the 7-inch layer and did the same. I swirled the waves in with an offset spatula.
  19. I used an edible ink pen to draw on the narwhal eyes. I thought about putting a smile on it too, but worried if I messed it up, it'd look creepy.
  20. Add the mermaid tail, narwhal front and tail, and the seascape items to the cake. Serve with lots of hugs, virtual for friends and big squeezes for immediate family and housemates.


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